SNAIL 



SNAKE RIVER 



whorl but one, it is often strengthened by an inter- 

 nal thickened ri)>, its edges are usually more or 

 less rellexe<l, and tin-re are sometimes calcareous 

 tooth-like prominences known as the denticles or 

 apertural lamelhp. The animal progresses u|>on a 

 f.Hii or sole, hirli is llattened beneath, and fringed 

 at the edge. There are four retractile tentacles, 

 the two upper ones the largest, and tearing the 

 > cs. There is a crescent-shaped jaw, which is 

 usually strongly ribbed. The tongue or lingual 

 membrane l>ears very many teeth arranged in 

 transverse rows. Thus, the Common Garden Snail 

 has 135 rows of 105 teetli 14.17.~> in all. Snails 

 are hermaphrodite, but mutual impregnation takes 

 place. They are provided with calcareous styles or 

 darte, which are secreted within a sac, the dart- 

 sac, from whieh they are protruded 

 during copulation. The forms of these 

 darts are very various, and sometimes 

 offer excellent characters for the separa- 

 tion of allied species. The eggs of 

 snails are round or oval, and are de- 

 posited in damp places or in the earth. 

 Those of the Edible Snail are nearly 

 as large as a pea. At the approach of 

 winter, or in very dry weather, snails 

 close the mouth of the shell with a 

 membrane (epiphragm) formed by the 

 Fi 2 drying of the mucous substance which 

 ' Darte ' of tne y 8ecrete > an< ^ become inactive and 

 ."n.iil-- torpid. Some, as the Edible Snail, 

 a Helix atpena- make * succession of such membranes, 

 i>, lldirartnu- the outer one of which is also strength- 

 toruM. ened by a quantity of calcareous mat- 



ter, the secretion being at first a white 

 viscid fluid, but quickly hardening like plaster of 

 I'aris. When this is to be removed a fresh secre- 

 tion of fluid mucus softens it at the edges. The 

 Common Garden Snail is to some extent gregari- 

 ous when in the torpid state : many individuals 

 may frequently be found closely packed together 

 in cracks in walls, under loj>3 or stones, and in 

 other sheltered places. Snails delight in warm 

 iiini-t weather, and are active chiefly at night and 

 during or after rain. They are also more abundant 

 on limestone soils than elsewhere ; the kinds found 

 in districts where there is little or no lime have 

 frequently very thin shells, owing to the deficiency 

 of calcareous matter to strengthen them. Snails 

 feed chiefly on vegetable sul>stances, although they 

 are very indiscriminate in their appetite, and even 

 devour the dead of their own kind. The mischief 

 which they do to garden crops is too well known ; 

 and gardeners are constantly on the alert to destroy 

 them. Thrushes and blackfiirds devour great quan- 

 tities of snails ; they select a suitable stone against 

 which they break the shells. These ' breaking- 

 stones ' may often be found in fields and by road- 

 sides surrounded by fragments of shells. Snails 

 possess in a very high degree the power of repair- 

 ing injuries, and specimens may not rarely be 

 found in which part of the shell lias l>een broken 

 and repaired again. Snails are found in nearly 

 every part of the globe, some thousands of species 

 having )>cen descriltrd by authors. Seventy species 

 are found in the British Islands, of which twenty- 

 two belong to the genus Helix. The Edible or 

 Komiiii Snail ( H. jmmatia ), much esteemed as an 

 article of food on the Continent, is regularly bred 

 on large and prosperous snail-farm* in canton 

 Zurich, Itavaria. and elsewhere, being fed on salad, 

 greens, kitchen-waste, meal, &c. It is a large 

 tawny species, not rare in |>arts of the south of 

 England (especially Kent and Surrey), and is sold 

 for food in London. The Common Garden Snail (H. 

 (uperta), the most destructive species in Britain, 

 is too abundant in most place-, but rare in parts ot 

 Scotland and north-west England. It is also used 



for culinarv purges, notably in the Newcastle. 

 Bristol, and Swindon districts." The Striked Snail 

 ( //. nemoralii) is smaller than tlie Canlen Snail, 

 and of various colours, usually red or yellow, orna- 

 nienteil with one to five spiral dark brown Iwuids. 

 The rim or lip of the a|>erture in this specie- is dark 

 brown, lint in a closely allied species, //. horttnnt, 

 it is white. Both these species are very common, 

 and it is a favourite custom for collectors to olitain 

 large series showing the variation, their beauty and 

 interest being very great. Taking variations in 

 the banding alone, already eighty nine of H. 

 nemoralif and fifty of //. AortfMM have been 

 found within the British Islands, while very 

 many others are known from abroad. //. nemor- 

 a/is, when introduced into Virginia, produced 

 many band-variations which are not known in 

 Europe. H. arbustortim is a species alniut the 

 same size as //. nemoralis, but brown, mottled 

 with pale yellowish, and usually encircled by a 

 single dark Iwind. The Kentish Snail ( //. rmi- 

 ti/nin) is smaller, whitish, more or less tinged \\ith 

 rufous. The Hairy Snail (//. hisj>itln) is a small 

 horn-coloured or brown species found in hedges, 

 among moss, &c, ; it-s shell is clothed with minute 

 hairs or bristles. H. rirgata is a species rather 

 over i-inch in diameter, found very abundantly 

 in chalky places, on downs, and by the sea. It is 

 usually white with one or more dark-brown bands, 

 though some of the varieties are blackish or yel- 

 lowish. On the South Downs this and an allied 

 but smaller species ( //. caperata ) are so abundant 

 that the sheep, when feeding H]x>n the short grass, 

 can scarcely avoid devouring them ; and the excel- 

 lency of the South Down and Dartmoor mutton 

 has in part been attributed to the nutritive quali- 

 ties of the snails. H. ericetorum is another species 

 allied to //. rirgata, and found in similar places, 

 but it is larger and has the shell much flattened 

 above. H. iilrlirll<i is a minute but very l?auti- 

 ful species, found abundantly t>oth in Europe and 

 North America. Hyalinia (often called /unite.-) 

 is a genus of small snails in which the jaw is with- 

 out ribs, and the shell smooth and shiny. There 

 are eleven British species. Some of them emit a 

 garlic odour, especially //. al/iri. 11. cri/ttallina 

 is a small species of a clear white colour. The 

 genus Pupa consists of brown cylindrical shells, 

 re-eiiibling small seeds. Some of them, which are 

 placed in the sub-genus Vertigo, are exceedingly 

 minute. P. antivertigo has the aperture of the 

 shell so barred by long calcareous processes 

 (ili-iitirles) that it is a wonder how the animal 

 can emerge from it. i 'Ian-ilia is somewhat similar 

 to I'upa, out longer both actually and in propor- 

 tion to the width; the aperture "is turned to the 

 left (sinistral) instead of to the right (as is the 

 case with the majority of snails), and is provides! 

 with a very curious spiral, shelly plate (daiuium). 

 A south European snail (Stnmgyiii decollata) is of 

 a cylindrical shape, and sheds its upper whorls 

 when it l(ecomes adult, the aj>erture so formed 

 Iteing covered by a shelly plate. Adult specimens 

 thus appear truncate, presenting a very singular 

 appearance. See Rimmer's Land and fresh-water 

 Shells of the British Inlands ( 1880). 



Snake Bird. See DARTER, WRY-NECK. 



Snnke River, the largest affluent of the 

 Columbia River, rises among the Rocky Mountains 

 near the western border of Wyoming, sweeps in a 

 rough semicircle through southern Idaho, forming 

 here the famous Shoshone Falls (q.v.), and, turning 

 north, divides Idaho from Oregon and partly from 

 Washington. At Lewiston it turns westward, and 

 in southern Washington, under the name of the 

 Lewis River or Fork, joins the Columbia, after a 

 course of some 1050 miles. It traverses a very 



